World outrage grew Saturday as details emerged about an attack in the Syrian village of Houla , which left more than 90 people dead , including nearly three dozen children , according to the United Nations .

U.N. observers went to Houla and viewed the bodies , a day after opposition activists reported a massacre there at the hands of the Syrian regime . The activists said entire families were killed .

`` Whoever started , whoever responded and whoever took part in this deplorable act of violence should be held responsible , '' Maj. Gen. Robert Mood , the head of the U.N. Supervision Mission in Syria , said in a statement .

Thirty-two children under the age of 10 and more than 60 adults were killed Friday , the statement read . Circumstances that led to the deaths are unclear , he said .

Later , Mood told CNN that observers counted 85 bodies and that 34 of the dead were children under the age of 10 . The discrepancy with the earlier number could not immediately be explained .

Observers confirmed the use of artillery and tank shells , Mood said .

`` This indiscriminate and disproportionate use of force is unacceptable and unforgivable . The killing of innocent children and civilians needs to stop , '' said the major general .

He stressed that unarmed U.N. observers are just `` one small ingredient '' in the effort to end the ongoing violence in Syria .

`` At some point , obviously , there will be a discussion about other alternatives and other ways forward , but that is a discussion that has to be within the context of the U.N. Security Council and the key stakeholders to all of this , '' Mood told CNN .

Syrian state media reported the observers ' visits Saturday to several towns and cities and blamed al Qaeda-linked groups for the deaths in Houla .

State TV broadcast Houla images filmed by opposition activists and reported that `` more than 50 children were killed ... by criminals and killers who aim to hurt Syria . ''

The government has consistently blamed `` armed terrorists '' for violence in Syria .

Rebels leaders interpreted the latest massacre as evidence that a United Nations cease-fire and peace plan are n't working and called for retaliatory attacks .

`` We call on our fighters , the soldiers and the revolutionaries , to conduct organized and planned military strikes against Assad battalions and regime members , '' Brig. Gen. Mustafa Al-Sheikh , a top leader in the rebel group , said in a video statement posted on YouTube .

A network of Syrian opposition activists , the Local Coordination Committees of Syria , blamed `` forces and armed militias '' of the Syrian government for `` a new massacre '' in Houla .

`` This barbaric act was preceded by the regime 's mortar shelling in the town , '' the LCC said in a statement . `` The campaign ended when the armed militias slaughtered entire families in cold blood . ''

Graphic video posted on YouTube purportedly shows the lifeless bodies of small children killed in Houla . They are spread on the floor amid blankets , caked in blood . One child is turned to reveal a head wound .

CNN could not independently confirm the authenticity of the video , nor can it confirm reports from within the country because the government strictly limits access by foreign journalists .

In a joint statement with U.N. Secretary-General Ban Ki-moon , joint special envoy to Syria Kofi Annan said he is contacting Syrian authorities `` to convey in the clearest terms the expectations of the international community . ''

`` This appalling and brutal crime involving indiscriminate and disproportionate use of force is a flagrant violation of international law and of the commitments of the Syrian government to cease the use of heavy weapons in population centers and violence in all its forms , '' the joint statement said . `` Those responsible for perpetrating this crime must be held to account . ''

U.S. Secretary of State Hillary Clinton condemned the Houla killings .

`` Those who perpetrated this atrocity must be identified and held to account , '' Clinton said in a statement . `` And the United States will work with the international community to intensify our pressure on -LRB- Syrian President Bashar al-Assad -RRB- and his cronies , whose rule by murder and fear must come to an end . ''

Turkey 's President on Egypt , Syria and Israel

Lt. Bassim al-Khaled , a spokesman of the rebel Free Syrian Movement , said more bloodshed is forthcoming . The al-Assad government is using the cease-fire and peace plan `` to kill more people and is trying to crush the uprising , '' al-Khaled said .

`` So the only language this regime is going to understand is the language of the gun . Wait and see , we will make them pay for each drop of blood which was shed , '' al-Khaled said .

Britain also condemned the massacre , calling Saturday for an urgent session of the U.N. Security Council and a full account of the `` appalling crime . ''

More regime attacks Saturday killed 60 people across the country , including 25 in Homs , just south of Houla , according to the Local Coordination Committees .

The Local Coordination Committees earlier Saturday decried the world 's `` apparent blindness '' to the violence in Syria .

Months of U.N. Security Council attempts to resolve the crisis have failed to have any effect .

Ban said Friday the full cadre of 300 U.N. observers authorized by the Council will be in Syria in the coming days .

Ban issued a sobering report Friday on the Syrian crisis , detailing `` continuing reports of a stepped-up security crackdown by the authorities that has led to massive violations of humans rights ... including arbitrary arrests , torture , enforced disappearance and summary execution of activists , opponents and defectors . ''

In a letter to the head of the U.N. Security Council , obtained by CNN , Ban said he is deeply concerned that the Syrian violence has not stopped despite the presence of the monitors and the agreement by both sides to a peace plan .

U.N. officials say more than 9,000 people , mostly civilians , have died and tens of thousands have been uprooted since the uprising began in March 2011 . Opposition groups report a death toll of more than 11,000 people . Since al-Assad 's government and opposition forces accepted Annan 's peace plan in March , at least 1,635 people have been killed , the LCC said Saturday .

Following the reported massacre in Houla on Friday , the rebel Free Syrian Army implored members of the international `` Friends of Syria '' group to form a military coalition to launch airstrikes against al-Assad forces .

Meanwhile , the state-run Syrian Arab News Agency -LRB- SANA -RRB- said that `` al-Qaeda-linked terrorist groups '' massacred a couple and their six sons and a father and son in the rural village of al-Shumariyeh village in the Homs province .

The agency also said similar terrorist groups massacred a family of seven , including three children , in the same province 's rural town of Taldo . The groups also burned houses and crops and blamed the army for bombarding the area , SANA reported . The terror group also sabotaged the National Hospital in the area and attacked a law enforcement headquarters , SANA said .

@highlight

Leader of the Free Syrian Army calls for retaliatory attacks against the government

@highlight

Syrian state media says al Qaeda-linked groups are responsible for the violence

@highlight

U.N. observers see the bodies of close to three dozen children

@highlight

Major general : `` Whoever took part in this deplorable act ... should be held responsible ''